On Tuesday morning, Hardy received a phone call from Tina Cook, who, for the past 16 years, has run a Facebook group -- Veteran Buddy Finder -- that helps veterans find each other.

Cook told ABC News she used a genealogy website and a newspaper archive website to find mentions of Whiteman, and ultimately found a living relative of his in Missouri.

That relative, Whiteman’s former sister-in-law Phyllis Lawson, said she was shocked to get phone calls from Cook and Hardy yesterday letting her know that Whiteman’s Purple Heart had been found in Arizona.

“There’s a mystery person out there somewhere that gave that to the Goodwill,” Lawson, 68, told ABC News. “I have no idea how it got there.”

Lawson, of Holts Summit, Missouri, was married to Whiteman’s younger brother, Robert Alan Whiteman, who she says passed away in 2013. The couple divorced in the 1980s and Lawson says she never knew much about Eual Whiteman, who was much older than his brother.

“He and my ex-husband were 16 years apart and he left for the military when Robert was extremely young and then he just kind of stayed gone,” Lawson said. “He came home once a few weeks after his mother died and stayed about a week and then he was gone again.”

Whiteman died in 1991 and is buried in the Willamette National Cemetery in Oregon, according to military records. The Missouri native enlisted in the U.S. Army in 1940. Cook’s research found that Whiteman earned three battle stars, a Combat Badge and a Presidential Unit Badge with the 82nd Airborne Division, in addition to the Purple Heart.

“He never had any children,” Lawson said of her former brother-in-law, who once appeared on the cover of Life magazine as a bull rider. “It’s sad that it ended up [at Goodwill] and sad that he wasn’t with family.”

Hardy plans to mail the Purple Heart to Lawson in Missouri today. She said her grandfather was also a Purple Heart recipient whose medal is in a museum, so she wants to make sure Whiteman's medal is with his family.

“It belongs somewhere where people can honor it or at least be with the family,” Hardy said. “I just thought it was unbelievable, all the people who tried to help, from all over the country people were on their computers trying to find this man.”

Goodwill says it was "unfortunate" that the Purple Heart ended up for sale and that they have offered to reimburse Hardy the $4.99 sale price.

"We have a process in place for all of our donation attendants that when they identify an item of significance, like a medal, we ask them to pull it aside and we try to contact either the Veterans Affairs Department or local authorities," Courtney Nelson, vice president of marketing and communications for Goodwill of Central Arizona, told ABC News. "They are processing thousands of items every day so this was unfortunately an example of an item that slipped through and wasn’t identified as a Purple Heart."